PSI - Issue 18

Valerii Matveenko et al. / Procedia Structural Integrity 18 (2019) 12–19 Author name / Structural Integrity Procedia 00 (2019) 000–000

17

6

Table 3. The calculations results for fiber glued across its length with various parameters of the adhesive layer a/d b/d 1 o  2 o  3 o    * 1 o     * 2 o   1  % 2  % 0.16 4.8 0.26 -0.05 -0.23 -0.236 -0.186 29.27 1.90 0.32 4.8 0.21 -0.03 -0.23 -0.224 -0.186 23.25 2.35 0.64 4.8 0.14 0.01 -0.23 -0.208 -0.187 14.31 2.48 0.16 9.6 0.39 -0.08 -0.23 -0.269 -0.194 47.48 6.58 0.32 9.6 0.36 -0.06 -0.23 -0.261 -0.195 43.10 6.92 0.64 9.6 0.30 -0.04 -0.23 -0.248 -0.194 35.80 6.29

To test the defect registration method, the rectangular samples considered in the work with sensor grid (s1-s6) and with holes with a diameter of 2, 4, 6, 8 mm were tested. The scheme of the sample is shown in the Fig. 3. In the experiments under consideration, the holes imitate the appearance and development of damage.

Fig. 3. Rectangular samples with hole.

For plates with different holes, numerical calculations of the stress-strain state based on the finite element method were performed. The difference between the calculation results and the experimental data do not exceed 6%. According to the proposed method, in the problem under consideration there is one loading option, i.e. n=1 in equation (1). For the presented sensor grid, the following 15 strain relations will take place:

 



 



 

 

(6)

,

, , 

,

,

, , 

a

a

a

a

a

a













5

1

1

1

2

2

12

13

16

23

24

56





2

3

6

3

4

6

Here 1 2 3 , ,    - strain tensor component y  , measured by sensors s1, s2, s3; 4 5 6 , ,    - strain tensor component x  , measured by sensors s4, s5, s6. Fig. 4 shows the dependence of some ratios pq a on the diameter of the hole. In this case, the hole imitates damage, and an increase in its diameter corresponds to the damage development. It should be noted that the values pq a based on the assumption of a linear elastic behavior, do not depend on the level of load 0 P . This proposal was confirmed by the results of the experiment.